Introduction to Liquid Crystal Displays

The most common application of liquid crystal technology is in liquid crystal
displays (LCDs). From the ubiquitous wrist watch and pocket calculator to an
advanced VGA computer screen, this type of display has evolved into an
important and versatile interface.

A liquid crystal display consists of an array of tiny segments (called
pixels) that can be manipulated to present information. This basic idea is
common to all displays, ranging from simple calculators to a full color LCD
television.

Why are liquid crystal displays important? The first factor is size. As will
be shown in the following sections, an LCD consists primarily of two glass
plates with some liquid crystal material between them. There is no bulky
picture tube. This makes LCDs practical for applications where size (as well as
weight) are important.

In general, LCDs use much less power than their cathode-ray tube (CRT)
counterparts. Many LCDs are reflective, meaning that they use only ambient
light to illuminate the display. Even displays that do require an external
light source (i.e. computer displays) consume much less power than CRT devices.

Liquid crystal displays do have drawbacks, and these are the subject of
intense research. Problems with viewing angle, contrast ratio, and response
time still need to be solved before the LCD replaces the cathode-ray tube. However
with the rate of technological innovation, this day may not be too far into the
future.

We will restrict this discussion to traditional nematic LCDs since the major
technological advances have been developed for this group of devices. Other LC
applications, such as those employing polymer stabilization of LC structure,
are discussed in the appropriate section covering those materials.

For a more detailed look at liquid crystal displays, follow this link.